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Richard Erlacher
08/21/12 21:11
Read: 503 times
Denver, Co

#188110 - Have you considered silicone coating?
Responding to: David Brown's previous message
There are a few alloys of silicone that you could use as a non-conductive inert and waterproof coating. Sadly, they're not particularly cheap, but they do serve. I've used Dow-Corning type 734 for a number of applications, including this one, with success.

My experience has only used lower voltages, i.e. 3V3 to unregulated 10 volts. Lab experience (other folks' labs) have taught me that voltages above 28 volts are to be avoided. That was, in the past for reasons mostly associated with fire and sparking, but the higher the voltage, the better the insulation has to be.

With a careful application, the type 734 sealant (there are competing products, but read and understand the spec's) can be applied in a way to make a common membrane keypad quite waterproof. The clear version, which is what I've used, is translucent and, applied very thin, can be quite transparent, certainly enough to read labels larger than 10 point type.

It's not expensive enough to prevent a few trials, BTW.


List of 22 messages in thread
Designing a product for use in water      David Brown      08/21/12 17:39      
   Have you considered silicone coating?      Richard Erlacher      08/21/12 21:11      
   one link      Stefan KAnev      08/21/12 22:04      
   Waterproof enclosures      Oliver Sedlacek      08/22/12 02:12      
      Projective touch - or maybe waterproof tablet      Per Westermark      08/22/12 06:27      
         If that potentiometer wasn't a hard requirement      Erik Malund      08/22/12 08:00      
            more details      David Brown      08/22/12 10:54      
               You might want to look into that a bit further      Richard Erlacher      08/22/12 13:33      
                  buttons for up/down gives tactile feedback      Per Westermark      08/22/12 14:12      
                     nevertheless, a strobe wheel rather than a pot ...      Richard Erlacher      08/22/12 15:24      
                        more good ideas      David Brown      08/22/12 16:42      
   Go to the lowest practical voltage      Jim Granville      08/22/12 16:20      
      answers      David Brown      08/22/12 17:39      
         Electric shock and intrinsically safe      Oliver Sedlacek      08/23/12 02:11      
            Isolators      David Brown      08/23/12 19:13      
               a question and a reference      Erik Malund      08/24/12 07:05      
                  answers      David Brown      08/24/12 10:55      
                     tethered unit??      Erik Malund      08/24/12 12:12      
                        mounted display      David Brown      08/24/12 12:32      
                           have you considered a combination of battery and solar?      Richard Erlacher      08/24/12 14:56      
                              indoor pool      David Brown      08/27/12 10:24      
                           Wireless chargers      Oliver Sedlacek      08/27/12 15:30      

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